JPS63173689A - Transfer-type thermal recording medium - Google Patents

Abstract

PURPOSE:To eliminate scummings and obtain a sharp printing, by a method wherein a recording medium is formed by laminating a hot-melt layer containing the ester of a branched satd. primary alcohol etc. and a fatty acid etc. and a heat-softening coloring layer successively on a heat-resistant substrate. CONSTITUTION:On a heat-resistant substrate such as a good-heat resistance plastic film, cellophane, and condenser paper, a hot-melt layer containing an oil mainly composed of a branched satd. primary alcohol and/or the ester of the aforesaid alcohol and a fatty acid or a hydroxy-fatty acid. Furthermore, on the hot-melt layer, a thermal transfer ink layer made of a heat-softening coloring layer which exhibits tackiness due to heat and has no possibility of melting to become a low-viscosity liquid is laminated; in this manner, a transfer- type thermal recording medium is obtained. As the branched satd. primary alcohol, an oil shown by formula I (m, n each is an integer which satisfies 7 < m + n < 28) is preferably used.

Description

[Detailed Description of the Invention] [Technical Field] The present invention has a thermally transferable ink layer with a two-layered laminated structure, and enables clear recording without scumming even on transfer paper with poor surface smoothness. The present invention also relates to a transfer type thermosensitive recording medium that has excellent storage stability.

[Prior art]

The transfer type thermal recording method is popular as a plain paper recording method with a simple device, but the print quality is easily affected by the smoothness of the surface of the transfer paper, and it is difficult to use for transfer paper with a poor surface smoothness. It is difficult to print clearly.

In order to improve such defects, conventional methods include heat treatment after printing (Japanese Patent Laid-Open No. 58-76276), magnetic force (Japanese Patent Laid-Open No. 52-96549) or electrostatic force (Japanese Patent Laid-Open No. 55-65) during transfer.
No. 590) etc. are used. Alternatively, add a large amount of oily substance to reduce the melt viscosity during transfer (
JP-A-60-25762), thermally decomposable (JP-A-60-25762)
82389) and heat sensitization by adding a thermally expandable substance (Japanese Patent Application Laid-Open No. 60-25762).

In addition, a technique has been proposed to improve print quality by layering multiple layers of heat-melt ink, in which heat-melt inks with slightly different melting points are layered, and pigments are added to one or both of them. Add (Japanese Patent Application Laid-Open No. 59-224392
Techniques have been proposed, such as providing a layer made of a heat-fusible substance containing no coloring material on a heat-fusible ink layer (Japanese Patent Laid-Open No. 60-97888).

However, in this method of recording by transferring melted ink that has become a liquid, if the surface of the transfer paper has low smoothness, the print quality will be lower than that of paper with a highly smooth surface. After all, only inferior print quality was obtained, and the fundamental problem of transfer type thermal recording, in which print quality was dependent on the smoothness of the surface of the transfer paper, could not be fundamentally solved.

On the other hand, when thermal energy is applied, the ink, which is mainly composed of a resin that exhibits tackiness but does not melt into a low-viscosity liquid and has a certain degree of mechanical strength, can be applied to transfer paper, which has a poor surface smoothness. By using an ink that adheres to the convex portions of the surface and covers the concave portions, it is possible to print with high quality on a transfer paper whose surface has poor smoothness.

However, such resin inks require more energy to print than conventional wax inks, so it is necessary to use a support film with particularly high heat resistance, and it also reduces the lifespan of the thermal head. This is not desirable as it causes heat problems.

In addition, high-boiling point solvents such as phosphoric acid esters, phthalic acid esters, animal and vegetable oils, mineral oils, higher fatty acids, and higher alcohols are used in the coloring material layer that is in contact with the heat-resistant support, so that the coloring layer does not cause background smearing or decrease in resolution. Thermal transfer media have also been proposed (Japanese Patent Application Laid-open Nos. 60-239284 and 1982-239285), but these have low sensitivity and are difficult to print at high speed or with low energy; In order to prevent a decrease in resolution, it is necessary to add a large amount of the high boiling point solvent, which causes difficulties in the storage stability and coating properties of the thermal transfer medium.

Furthermore, in a thermal transfer material in which a first ink layer and a second ink layer are provided on a support, a method is also known in which mineral oil or vegetable oil such as machine oil, castor oil, olive oil, or rapeseed oil is contained in the first ink layer. (Unexamined Japanese Patent Publication No. 187593/1983)
. Although this product has the advantage of being able to print well even in solid black without line breakage in the so-called first ink layer, it has the drawbacks of being prone to scumming and having poor storage stability.

〔the purpose〕

SUMMARY OF THE INVENTION An object of the present invention is to provide a transfer type heat-sensitive recording medium that enables clear printing without scumming even on transfer paper with poor surface smoothness and has good storage stability.

〔composition〕

According to the present invention, on a heat-resistant support, there is provided a heat-fusible layer that is prepared to melt at least into a low-viscosity liquid when heated, and a heat-meltable layer that exhibits adhesiveness when heated but melts to become a low-viscosity liquid. In a transfer type heat-sensitive recording medium in which heat-transferable ink layers consisting of heat-softening colored layers prepared so as to be laminated in that order,
There is provided a transfer type heat-sensitive recording medium characterized in that the heat-fusible layer contains an oil whose main component is a branched saturated primary alcohol and/or an ester of the alcohol and a fatty acid or an oxyfatty acid.

The transfer type heat-sensitive recording medium of the present invention comprises a heat-resistant support, a heat-meltable layer prepared to at least melt into a low-viscosity liquid, and a heat-meltable layer that exhibits tackiness when heated, but melts into a low-viscosity liquid. In a transfer-type heat-sensitive recording medium in which a heat-transferable ink layer consisting of a heat-softening colored layer is laminated in that order, the heat-melting layer has a low viscosity, extremely low volatile content, and a long lifespan. Because it contains a branched saturated primary alcohol whose properties do not deteriorate even when stored over time and/or an oil whose main components are an ester of the alcohol and fatty acid or oxyfatty acid, it is suitable for transfer paper with poor smoothness. It has extremely high practical value because it can print clearly without background smudges and has good storage stability.

Next, the present invention will be explained in more detail.

The heat-fusible layer in the present invention needs to be easily peelable from the support during printing.

For this purpose, it is sufficient that the material is configured such that after being heated, it is thermally melted to become a low-viscosity liquid, and the layer is easily broken near the interface between the heated portion and the non-heated portion.

Therefore, as the main component of the heat-fusible layer, a wax-like substance that is hard at room temperature and melts when heated is preferably used.

Such wax-like substances include, for example, beeswax,
Natural waxes such as carnauba wax, whale wax, wood wax, candelilla wax, Nuka wax, and montan wax,
paraffin wax, microcrystalline wax,
Synthetic waxes such as oxidized wax, osikerite, ceresin, ester wax, and polyethylene wax are preferably used, as well as higher fatty acids such as margaric acid, lauric acid, myristic acid, palmitic acid, stearic acid, fromene acid, and behenic acid, and stearyl alcohol. , higher alcohols such as behenyl alcohol, esters such as fatty acid ester of sorbitan, and amides such as stearinamide and oleinamide.

Further, in the present invention, as described above, the heat-fusible layer contains an oil whose essential component is a branched saturated primary alcohol and/or an ester of the alcohol and a fatty acid or an oxyfatty acid.

As the branched saturated primary alcohol, a compound represented by the general formula (1) is used.

(In the formula, m and n may be the same or different 7
It is an integer satisfying < m + n < 28. ) Examples of the branched saturated alcohol represented by the general formula CI) include the following.

Furthermore, typical examples of fatty acids include caproic acid, enanthic acid, caprylic acid, undecanoic acid, lauric acid, tridecanoic acid, myristic acid, pentadecanoic acid, palmitic acid, stearic acid, oleic acid, elaidic acid, linoleic acid, and lysyllic acid. , stearolic acid, arachidic acid, isooctanoic acid, isostearic acid, caproleic acid, 9-
Landecylenic acid, 10-landecylenic acid, 2-lauroleic acid, Linderic acid, Tuccinic acid, 5-Lauroleic acid, 11-Lauroleic acid, Tuduic acid, 5-Myristoleic acid, Myristoleic acid, 2-Palmitoleic acid, Cimaric acid, trans -9-palmitoleic acid, petroselic acid, petroselaidic acid, parsenic acid, bondoic acid, trans-bondooleic acid, sorbic acid, rhinoelaidic acid, α-eleostearic acid, β-eleostearic acid, lyrunelaidic acid , pseudoeleostearic acid, α-parinaic acid.

Examples include β-parinaic acid, arachidonic acid, and isooleic acid.

Further, examples of oxyfatty acids include sabinic acid, juniperic acid, lanopalminic acid, lysyllic acid, dioxystearic acid, and the like.

In addition, 1 the alcohol or ester used in the present invention is 2
It is preferable to have a viscosity of 100 cps or less at 5° C.; a viscosity exceeding 100 cps (25° C.) is not suitable because it lowers sensitivity and tends to cause thin wire breakage.

The amount of the alcohol or ester used in the heat-fusible layer is preferably 10 to 50 2 by weight. If it is less than 10% by weight, the effect will be poor, and if it exceeds 50% by weight, the adhesive strength will decrease and scumming will occur, which is not desirable.

The heat-fusible layer of the present invention further includes polyamide resins, polyester resins, epoxy resins, polyurethane resins,
Nydistomers such as acrylic resin, vinyl chloride resin, cellulose resin, polyvinyl alcohol resin, petroleum resin, phenolic resin, styrene resin, natural rubber, styrene-butadiene rubber, isoprene rubber, and chloroprene rubber are also used. However, the amount added is preferably 0 to 20% by weight of the heat-fusible layer.

Furthermore, if a colorant is included in this heat-fusible layer, the releasability of the layer from the support will be impaired, so addition of such a colorant should generally be avoided.

However, if sufficient density cannot be obtained with the heat-softening colored layer alone, or if the hardness of the layer is adjusted,
A coloring agent may be added as long as it is 5% by weight or less.

Unlike the heat-melting layer, the heat-softening colored layer does not have a clear melting point and becomes sticky to the transfer paper due to the thermal energy during recording, but it is made of a resin that does not melt into a low-viscosity liquid. This layer is the main component, and due to the function of this layer, each of these resins has a tensile strength (JIS
K 6760-1966) is preferably 20 kg/rrr or more.

Preferred examples of such resins include ethylene-vinyl acetate copolymer, ethylene-ethyl acrylate copolymer, and polyester resin, as well as polyamide resin,
Epoxy resin, polyurethane resin, acrylic resin,
Vinyl chloride resin, cellulose resin, polyvinyl alcohol resin.

Examples include elastomers such as petroleum resins, phenolic resins, styrene resins, natural rubber, styrene-butadiene rubber, isoprene rubber, and chloroprene rubber. In addition, tackifiers such as terpene resins, coumaron resins, rosin and their derivatives, and waxes used in the heat-melting layer can be added as auxiliary materials to these resins, but the total amount of them is It is desirable that the weight of all the resin components of the colored layer is 60% by weight or less.

Since the heat-softening colored layer is the main component transferred during recording, it must contain a colorant, but the amount should be adjusted to an appropriate level from the viewpoint of sensitivity during recording, storage performance, print quality, etc. However, an excessive amount is not desirable, and it is preferably 70% by weight or less of the total dry weight of the heat-softening colored layer.

The colorant used in the present invention is appropriately selected from conventionally known dyes and pigments.

Basic dyes, oil-soluble dyes, acid dyes, direct dyes, disperse dyes, etc. are preferably used, and as pigments, carbon black, phthalocyanine pigments, etc. are preferably used.

Further, the thickness of the heat-fusible layer is preferably 2 to 10 μm, and the thickness of the heat-softening colored layer is preferably 0.5 to 5 μm. Further, the total thickness of the thermally transferable ink layer is preferably 4 to 20 μm.

Additionally, additives such as a dispersant, a penetrant, an adhesion modifier, and a fluidity control agent may be added to the heat-melting layer and the heat-softening colored layer, respectively, if necessary.

In addition, as a support, relatively heat-resistant plastic films such as polyester, polycarbonate, triacetylcellulose, nylon, and polyimide, cellophane, parchment paper, condenser paper, etc. can be used, and if necessary, the thermal head of the support can be used. Silicone resin, fluororesin, polyimide resin, epoxy resin, phenol resin,
A heat-resistant image eM such as melamine resin or nitrocellulose or a stick prevention layer such as wax may be provided.

The thickness of the support is preferably 2 to 6 μ-, but it may be 2 to 6 μ- thick if used or treated to improve heat transfer efficiency.
Thicknesses up to 20 μm can be used.

The two-layer laminated transfer type thermosensitive recording medium of the present invention as described above can be prepared by coating the support film with a hot melt method, a solvent dispersion coating method,
It is obtained by applying the components forming each layer using a water-based emulsion coating method or the like.

〔Example〕

The present invention will be explained below using Examples.

Example 1 [Thermofusible layer forming component] Paraffin wax (m, p, 65° C.) 80 parts by weight The above mixture was heated and then dispersed in a ball mill for 3 hours to obtain a thermofusible layer forming liquid.

[Formation component of heat-softening colored layer]

Carbon black 20〃Polyethylene wax (m, p, 100°C) 20nThe above mixture was dispersed under heating in 300 parts by weight of toluene using an attritor to obtain a heat-softening colored layer forming liquid.

Next, the heat-melt layer forming liquid was applied to a 3.5-μm-thick polyester film by a hot-melt coating method to form a 6-μI-thick heat-melt layer. Next, the heat-softening colored layer forming liquid was applied onto the heat-melting layer using a wire bar and dried.

A heat-softening colored layer having a thickness of 3 μm was formed to obtain a transfer type heat-sensitive recording medium of the present invention.

Example 2 A transfer type thermosensitive recording medium of the present invention was obtained in the same manner as in Example 1, except that the components forming the heat-fusible layer and heat-softening colored layer in Example 1 were replaced with the following.

[Components forming the thermofusible layer]

Candelilla wax (m, p, 68°C) 70 parts by weight Carbon black 5 [Component for forming the heat-softening colored layer] Carbon black 10 Comparative example 1 Branched saturation, which is the component for forming the heat-meltable layer in Example 1 A comparative transfer type thermosensitive recording medium was obtained in the same manner as in Example 1 except that the primary alcohol was omitted.

Comparative Example 2 A comparative transfer-type thermosensitive recording medium was obtained in the same manner as in Example 2, except that the branched saturated primary alcohol, which was a component forming the heat-fusible layer in Example 2, was omitted.

Comparative Example 3 A comparative transfer-type thermosensitive recording medium was obtained in the same manner as in Example 1, except that the branched saturated primary alcohol, which was a forming component of the heat-fusible layer in Example 1, was replaced with liquid paraffin.

Comparative Example 4 A comparative transfer-type thermosensitive recording medium was obtained in the same manner as in Example 2, except that rapeseed oil was used for the branched saturated primary alcohol and ester of oleic acid, which were the forming components of the heat-fusible layer in Example 2. .

Next, using each of the thermal recording media obtained above, printing was performed on bond paper (smoothness: 20 seconds) using a commercially available thermal printer (JP-300; manufactured by Ricoh Co., Ltd.), and the printing quality, background smearing, and its preservation were I looked into gender.

The results are shown in Table-1.

Table 1 [Effects] The transfer type thermal recording medium of the present invention is capable of making clear records without background stains even on transfer paper with poor surface smoothness, and has excellent storage stability. be.

Claims (2)

[Claims] (1) On a heat-resistant support, there is a heat-fusible layer prepared to at least melt under heat to become a low-viscosity liquid, and a heat-fusible layer that exhibits stickiness when heated but does not melt to become a low-viscosity liquid. In a transfer-type heat-sensitive recording medium in which heat-transferable ink layers consisting of the prepared heat-softening colored layers are laminated in that order, the heat-fusible layer is coated with a branched saturated primary alcohol and/or an ester of the alcohol and a fatty acid or an oxyfatty acid. A transfer type heat-sensitive recording medium characterized by containing oil as a main component. (2) The transfer type thermosensitive recording medium according to claim 1, wherein the branched saturated primary alcohol is an oil represented by the following general formula. ▲There are mathematical formulas, chemical formulas, tables, etc.▼ (In the formula, m and n may be the same or different 7
It is an integer satisfying <m+n<28. )